Solar Light (Heat) Absorption Material and Heat Absorption/Accumulation Material and Solar Light (Heat) Absorption/Control Building Component Using the Same

ABSTRACT

A solar light (heat) absorption material is provided which has an excellent solar light (heat) absorbing ability and a simple structure, and may be usable as a low-cost and high-performance heat absorption/accumulation material, the inventive material being usable also as a solar light (heat) absorption/control building component that allows easy change of its solar light (heat) absorption/control ability. The material comprises particles dispersed into a liquid medium having a specific heat ranging from 0.4 to 1.4 cal/g/° C. and a melting point of 5° C. or lower. The dispersed particles have L*value of 30 or less as determined by the CIE-Lab color system (light source D65).

TECHNICAL FIELD

The present invention relates to a solar light (heat) absorptionmaterial having excellent solar light (heat) absorption. Moreparticularly, the invention relates to a heat absorption/accumulationmaterial utilizing the solar light (heat) absorption material comprisinga heat absorbent material and a heat accumulation material integratedtogether, thus achieving less heat loss from the heatabsorption/accumulation material, so that the heatabsorption/accumulation material has excellent solar heat-absorbingefficiency and relates also to a heat absorption/accumulation structure,a cooling system or a power generating system utilizing the heatabsorption/accumulation material.

The invention also relates to a solar light (heat) absorption/controlbuilding component using the above-described solar light (heat)absorption material and having excellent ability to absorb/control solarlight (heat), the solar light (heat) absorption/control buildingcomponent allowing easy change in this absorption/control ability. Theinvention further relates to an agricultural/horticultural facility anda house/building using the inventive material.

BACKGROUND ART

Recently, the earth has been facing serious problems such as globalwarming, depletion of fossil fuels, etc. For sustainable development infuture, there are high expectations for utilization of solar heat. Asexamples of solar heat utilization, there have been conventionallypracticed converting water into hot water by a solar water heater. to beused directly for a shower or bathing, using heat thereof for generationof electricity, air cooling.

As some examples of solar water heater, there are known a tank-reservedtype water heater including a heat collecting portion and a heataccumulating portion formed integral with each other, a naturalcirculation type including a heat collecting portion and a heataccumulating portion as separate portions and a forced circulation typewater heater. Though differing in the operating principles thereof, thebasic operational principle common to these water heaters resides in useof the solar heat absorption material (heat collecting plate) andtransfer of an amount of heat collected therein to the heat accumulatingportion (generally, water) to be accumulated therein. Conventionally,for solar water heaters, research has been done for the purpose ofperformance improvement thereof, to increase the absorbing efficiencyfor solar heat, to restrict heat loss from the heat collecting plate, toincrease the temperature of the heat accumulating portion. On the otherhand, reduction of the manufacturing cost has also been attempted.

Of the above-described aspects, the most focusing material of all is thesolar heat absorption material. So far, there has been developed a blackmaterial which absorbs the light of 2.5 μm or less which is present moreabundantly in the spectra (ultraviolet radiation, visible light,infrared radiation) of solar light reaching the earth surface, such asblack-colored inorganic materials such as metal oxide such as chromiumoxide (black chrome), nickel oxide (black nickel), copper oxide, zincoxide, iron oxide, etc or organic substances (Patent Documents 1 through4). However, all of these are expensive, thus going counter to the needfor manufacturing cost restriction.

Further, in view of the fact that for elevating the temperature of theheat accumulating portion, the most effective measure is to increase thelight collecting area for the solar light and to restrict heat loss fromthe heat accumulating plate; hence, various proposals have been made(Patent Documents 5 through 16).

However, all of these, based fundamentally on the same principle, havebeen unable to achieve performance improvement, cost reduction anddownsizing of any significant degrees. That is, with those constructionsof solar water heaters proposed so far, improvement of solar lightabsorbing efficiency and elevating the temperature of light collectingplate are essentially required for improvement of heat conductivity tothe heat accumulating portion. However, when these measures are taken,there inevitably occurs increase of heat loss from the light collectingplate (black-body radiations ≡ σT⁴). In order to restrict this heatdissipation, it has been required to provide a selective absorptionmembrane, to evacuate the space where the light collecting plate isinstalled or to charge an amount of rare gas therein, these are invitinggreater complexity, enlargement and cost increase of the apparatus.

As described above, with the conventional solar water heaters, greatercomplexity, size enlargement, use of special material, etc. have beenrequired for improving performance and all of which lead to increase inthe manufacture cost. For this reason, the conventional heaters have notbeen widely popularized.

On the other hand, for growth of plants, the light, temperature,humidity, nutrition, water, or appropriate stress such as wind, etc. areneeded. In particular, the light and the temperature are significantlydependent upon the external environment and geographical factors,seasonal factors exert significant influences on the kinds and yields ofplants that can be cultivated. In subtropical and tropical regions atlow latitudes, it is extremely important how the amount of solar lightis to be restricted and/or what temperature is to be controlled forappropriate culture of plants. At present, culturing of crops not suitedto the geographical conditions must simply be given up. Also, in coldzones, an enormous amount of energy is needed for elevating atemperature suitable for culture. And, an enormous amount of electricenergy is needed for ensuring sufficient light amount.

Patent Documents 17 through 19 identified below describe placing alight-shielding film sheet over a crop plant or an agricultural housefor restricting the large amount of solar light (heat). These solarlight (heat) absorption/control building components are formed byincorporating in the agricultural film sheet a substance which restrictssolar light, so that the materials constantly cut the solar beam by apredetermined ratio. Notwithstanding, these materials do not allowchange of their ability to absorb/control the solar light (heat).Therefore, as these materials shield a fixed amount of solar light evenat hours or on a day when the amount of solar radiation is small, suchas at the morning or evening hours or on a cloudy day. Hence, theyprovide adverse effect to the culture of crop plants due to the amountof light falling far below the amount suitable for their culture.

Further, in a house or a building too, its roof or wall is heated due todaytime solar radiation, so that there occurs rise in the temperature inthe living space inside, thus deteriorating the living environment. Ifair conditioning is effected for reducing the temperature rise, theamount of electric energy required therefor will be enormous, thuspromoting the global warming, hence causing vicious cycle.

Patent Documents 20 through 22 identified below describe heat-insulatingfilms for restricting entrance of solar radiation through windows forpreventing the above problem. However, these conventional solar light(heat) absorption/control building components are also unable to allowchange of their ability to absorb/control the solar light (heat). Hence,these materials can be disadvantageous in the autumn/winter seasons oron cloudy days when the amount of solar radiation is small. Moreover,although the convention has provided some improvements in the heatinsulating material for building wall or roof or method of heatinsulation, as these heat insulating methods are passive heat insulationmethods, these suffer the problem that the temperature of the heatinsulating material per se rises, in accordance of which its heatinsulating effect deteriorates over time.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2001-99497-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 7-139819-   Patent Document 3: Japanese Unexamined Patent Application    Publication No. 2006-336960-   Patent Document 4: Japanese Unexamined Patent Application    Publication No. 2006-214654-   Patent Document 5: Japanese Unexamined Patent Application    Publication No. 2008-138899-   Patent Document 6: Japanese Unexamined Patent Application    Publication No. 2004-176966-   Patent Document 7: Japanese Unexamined Patent Application    Publication (Translation of PCT Application) No. 2008-542681-   Patent Document 8: Japanese Unexamined Patent Application    Publication (Translation of PCT Application) No. 2002-517707-   Patent Document 9: Japanese Unexamined Patent Application    Publication No. 2000-88359-   Patent Document 10: Japanese Unexamined Patent Application    Publication No. 2008.133991-   Patent Document 11: Japanese Unexamined Patent Application    Publication No. 5-52427-   Patent Document 12: Japanese Unexamined Patent Application    Publication No. 6-137688-   Patent Document 13: Japanese Unexamined Patent Application    Publication No. 2004-176966-   Patent Document 14: Japanese Unexamined Patent Application    Publication No. 2005-265251-   Patent Document 15: Japanese Unexamined Patent Application    Publication No. 2004-116964-   Patent Document 16: Japanese Unexamined Patent Application    Publication (Translation of PCT Application) No. 11-512173-   Patent Document 17: Japanese Unexamined Patent Application    Publication No. 2004-65004-   Patent Document 18: Japanese Unexamined Patent Application    Publication No. 2009-45027-   Patent Document 19: Japanese Unexamined Patent Application    Publication No. 2006-340675-   Patent Document 20: Japanese Unexamined Patent Application    Publication No. 2001-287291-   Patent Document 21: Japanese Unexamined Patent Application    Publication No. 2006-144538-   Patent Document 22: Japanese Unexamined Patent Application    Publication No. 2009-169252

SUMMARY OF THE INVENTION Object to be Achieved by Invention

The present invention has been made in view of the above-described stateof the art. The invention purports to develop a solar light (heat)absorption material having excellent solar light (heat) absorbingability and to utilize this material to provide a low-cost,high-performance heat absorption/accumulation material having a simplestructure and also to provide a solar water heater, a cooling system, anelectricity generating system utilizing hot heat generated from thisheat absorption/accumulation material.

The invention further purports to utilize the above-described solarlight (heat) absorption material to provide a solar light (heat)absorption/control building component which allows easy change in itssolar light (heat) absorption/control ability and to provide also anagricultural/horticultural facility or a house/building that allowssaving of unnecessary cooling/heating energy, thus contributing tosaving of fossil fuel and preservation of global environment.

Means to Achieve Objects

The present inventors have conducted extensive research to resolve theabove-noted object and discovered that a dispersion material comprisingparticles of biomass char etc. dispersed in a medium such as water hasexcellent solar light (heat) absorption/control ability and that usingthis as a heat absorption/accumulation material will reverse theconventional concept of solar water heater, providing a structure inwhich a heat absorption material is dispersed and integrated into a heataccumulation material, thereby to make it possible to satisfy all of theconventionally incompatible requirements of simplification of thestructure, cost reduction and performance improvement.

It was also discovered that by changing the kind, size and/or dispersioncontent of the particles, the solar light (heat) absorption/controlability of the material can be easily changed. In this way, the presentinvention has been completed.

Namely, the present invention provides a solar light (heat) absorptionmaterial comprising particles, which have L*value of 30 or less asdetermined by the CIE-Lab color system (light source D65), dispersedinto a liquid medium having a specific heat ranging from 0.4 to 1.4cal/g/° C. and a melting point of 5° C. or lower.

Further, in the solar light (heat) absorption material, said particlescomprise carbonized materials of biomass having micropores such asbagasse. The presence of such micropores can achieve improvement in thedispersion of the particles, the absorbance of the solar light (heat).Furthermore, the utilization of biomass achieves increased safety,restriction of the load to the environment.

Further, the present invention comprises a heat absorption/accumulationmaterial formed of said solar light (heat) absorption material.

Further, there is provided a heat absorption/accumulation structurehaving said heat absorption/accumulation material filled in a containerhaving an opening thereof covered with a light transmitting body.

Further, there is provided a solar water heater, a cooling system and anelectricity generating system utilizing the above-described heatabsorption/accumulation structure.

Further, the present invention provides a solar light (heat)absorption/control building component comprising a hollow portion and anamount of said solar light (heat) absorption material filled in thehollow portion of a plate-like body having an upper face and a lowerface at least one of which has light transmission characteristics.

In the above-described solar light (heat) absorption/control buildingcomponent, the solar light (heat) absorption material is circulatedto/from an external instrument. With the above, it becomes possible todisperse the particles uniformly into the solar light (heat) absorptionmaterial and to utilize an amount of the solar heat absorbed andaccumulated in the solar light (heat) absorption material.

In the above-described solar light (heat) absorption/control buildingcomponent, the component further comprises a detecting means fordetecting a outside condition and an adjusting means for adjusting thelight absorbance of the solar light (heat) absorption material accordingto the outside condition.

With the above, it is possible to adjust the solar light (heat) to beabsorbed/controlled in accordance with the outside condition. Hence, thesolar radiation amount can be controlled to be constant irrespective ofinfluences from the time of the day, weather, the season, etc.

Further, in said solar light (heat) absorption/control buildingcomponent, said outside condition comprises lightness and/ortemperature.

Further, in said solar light (heat) absorption/control buildingcomponent, the component further comprises a converting means forconverting the solar heat absorbed by the solar light (heat) absorptionmaterial into hot water/air or cold water/air.

With the above, the solar heat absorbed and accumulated by the solarlight (heat) absorption material can be effectively utilized.

The solar light (heat) absorption/control building component is one of awindowpane, a roof tile, a roofing material.

Further, there is provided an agricultural/horticultural facility usingsaid solar light (heat) absorption/control building component in itswall and/or ceiling.

With the above, unneeded energy for cooling/warming can be eliminated inan agricultural/horticultural facility. Hence, it becomes also possibleto make significant contribution to the saving of fossil fuels andpreservation of the global environment.

Further, there is provided a house/building using said solar light(heat) absorption/control building component in at least a part of itswall, window, roof or roof top.

As the solar light (heat) absorption/control building componentfunctions as an excellent heat insulating material, it is possible toreduce the amount of energy required for temperature condition of theindoor space significantly. As a result, unneeded energy forcooling/warming can be eliminated in a house/building. Hence, it becomesalso possible to make significant contribution to the saving of fossilfuels and preservation of the global environment.

Effects of Invention

The solar light (heat) absorption material of the invention has anexcellent solar light (heat) absorbing ability. Further, as thismaterial uses char particles originated from harmless biomass, wastematerial can be effectively utilized and also the load to theenvironment can be alleviated. Further, in case this is used as a heatabsorption/accumulation material, as the particles of the heatabsorption material are dispersed into the liquid of the heataccumulation material and in association with rise in the temperature ofthe heat absorption material, the heat is transferred directly to theheat accumulation material around it, heat loss in the course of heatconduction process can be restricted. In the case of the convention, inassociation with temperature rise due to heat absorption, dissipation ofheat by black body radiation from the heat absorption material per seoccurs inevitably. On the other hand, in the case of the presentinvention, since the heat absorption material is dispersed into the heataccumulation material, all of the heat dissipation from the heatabsorption material is absorbed by the heat accumulation material. Inthis way, the heat loss in the heat conduction process is reduced and nodissipation of heat to the outside occurs, so the efficiency of thesolar heat absorption is high.

Further, in order to obtain high-temperature heat, the conventionaltechniques combine a light collecting plate having a large area and aheat accumulation tank having a small area. However, as the area of theheat collecting plate is increased, the amount of dissipation heatincreases correspondingly. Hence, there would be required a measure tocope with this, so the technique would suffer from this vicious cycleand the conventional technique was not found satisfactory in terms ofefficiency and cost.

In contrast, in the case of the present invention, the temperature ofthe accumulated heat can be controlled by adjustment of the thickness ofthe heat absorption/accumulation material layer. Therefore,high-temperature heat can be obtained extremely easily and at low cost.

Further, with the solar light (heat) absorption/control buildingcomponent of the present invention, its solar light (heat)absorption/control ability can be easily changed by changing the kind,size and/or dispersion content of the particles. Further, by using thiscomponent in an agricultural/horticultural facility or a house/building,excess energy for cooling/warming can be eliminated and it becomes alsopossible to make significant contribution to the saving of fossil fuelsand preservation of the global environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrating section view showing one embodiment of a heatabsorption/accumulation structure relating to the present invention,

FIG. 2 is a view showing a cooling system according to the presentinvention,

FIG. 3 are schematic views showing one embodiment of a solar light(heat) absorption/control building component according to the presentinvention, (a) being a perspective view, (b) being a plan view, (c)being a front view, (d) being a side view,

FIG. 4 is a diagrammatic view illustrating a model method of a pseudosolar radiation absorption experiment in EXAMPLE 2,

FIG. 5 is results of an absorption characteristics experiment in EXAMPLE3,

FIG. 6 is result of a temperature rise experiment in EXAMPLE 4,

FIG. 7 are SEM photographs of bagasse char at each carbonizationtemperature in EXAMPLE 5, (a) 300° C., (b) 400° C., (c) 500° C., (d)600° C., (e) 700° C., (f) 800° C.,

FIG. 8 is a relationship between the carbonization temperature ofbagasse char and the transmittance in UV-VIS region in EXAMPLE 5,

FIG. 9 is a relationship between the dispersion content of bagasse charand the transmittance in UV-VIS region in EXAMPLE 6,

FIG. 10 is a relationship between irradiation time of pseudo solar lightand the rate of temperature rise of absorption material in EXAMPLE 7,

FIG. 11 is a relationship between bagasse char dispersion content andthe rate of temperature rise of solar light (heat) absorption materialin EXAMPLE 7,

FIG. 12 is a relationship between intensity of pseudo solar light andthe transmittance of solar light (heat) absorption material in EXAMPLE8,

FIG. 13 is a bagasse char dispersion content required for maintaininglightness inside a house at 300 g mol/sec/m² when lightness of theoutside has changed in EXAMPLE 8,

FIG. 14 is a model diagram showing an example of using the solar light(heat) absorption/control building component as a heat insulatingmaterial in a house in EXAMPLE 9, and

FIG. 15 is a figure of reduction in cooling load in case the solar light(heat) absorption/control building component is employed as a heatinsulating material in a house in EXAMPLE 10.

MODES OF EMBODYING THE INVENTION

The solar light (heat) absorption material according to the presentinvention comprises particles, which have L*value of 30 or less asdetermined by the CIE-Lab color system (light source D65), dispersedinto a liquid medium having a specific heat ranging from 0.4 to 1.4cal/g/° C. and a melting point of 5° C. or lower.

The medium (dispersion) employed in the present invention is a mediumwhich is liquid at the normal temperature and has a specific heatranging from 0.4 to 1.4 cal/g/° C. and a melting point of 5° C. orlower. With choice of the specific heat and melting point in theabove-described respective ranges, the amount of the medium used can bemade appropriate and there is obtained cost advantage as well. Further,by choosing the melting point of 5° C. or lower, the medium becomesusable in many various places and hours of the day. Specifically, asexamples thereof, there can be cited water, aliphatic mono alcohol,aliphatic di-alcohol, hydrocarbon, etc. Water can be suitably useddirectly. However, in order to lower the melting point and/or restrictproliferation of bacteria or the like, water can be used with aninorganic material or an organic material dispersed or dissolvedtherein. The inorganic material includes a metal chloride such ascalcium chloride, sodium chloride, magnesium chloride, potassiumchloride, strontium chloride, lithium chloride, ammonium chloride,barium chloride, iron chloride, aluminum chloride, or a bromide of asimilar group. The organic material includes ethanol, ethylene glycol,propylene glycol, glycerin, sucrose, glucose, acetic acid, oxalic acid,succinic acid, lactic acid, dispersed or dissolved therein. As someexamples of aliphatic mono alcohol, there can be cited ethyl alcohol,propyl alcohol, butyl alcohol, amyl alcohol, hexane alcohol, etc. Assome examples of aliphatic di-alcohol, there can be cited ethyleneglycol, propylene glycol, polyethylene glycol, polypropylene glycol,etc. As some examples of hydrocarbon, there can be cited aromatichydrocarbons, or chlorinated aromatic hydrocarbons, such as paraffin,benzene, xylene, chlorobenzene, etc. In the respects of safety,readiness of handling, absence of corrosiveness, and low cost, water ismost preferred of the above-cited media. When high-temperature heat isneeded, ethylene glycol, glycerin, having a high boiling point ormixture solution of these with water will be used.

On the other hand, the color of the particles should be black forincreased absorption of solar light (heat). When represented in theCIE-Lab color system which is the international standard of representingcolor tones of objects, the particles have an L*value (L-value) of 30 orless which is the reference of whiteness and blackness of an object,preferably 28 or less, more preferably from 3 to 25. In the L*value, thevalue of 0 represents a black body, i.e. the reference of absorbing alllight, thus being most preferred. However, in order to render this value0 requires significant cost and yield will be poor also. As can beunderstood from its L*value, although the particles per se are capableof absorbing solar light, this is not suitable for adjustment of degreeof absorption or utilization of absorbed heat. Then, in the presentinvention, in order to enable adjustment of degree of absorption andutilization of absorbed heat, the particles are used as being dispersedin the medium. Specifically, biomass char, commercially available carbonblack, carbon nanotube, iron black, copper-iron black, other organicpigments, inorganic pigments, etc. can be cited as examples. However, inthe case of using iron black, copper-iron black, other organic pigments,inorganic pigments, etc., it is important that sufficient care be takenfor the safety, dispersion performance relative to the medium. On theother hand, biomass char is suitably used, since it is superior not onlyin the safety, but also in the dispersion performance relative to themedium, and provides less load to the environment. As some examples ofbiomass char, there can be cited bagasse waste of squeezed sugarcane,coffee residue, soybean milk residue, chaff, rice bran, sake lees afterfermentation of sake or liquor (“Moromi”), various kinds of naturalfibers, chars of woods. Different from artificial substance, thesebiomasses have fine pore structure due to biological phenomenon. And,such pore structure remains after carbonization and reduces the bulkspecific gravity and improves dispersion into the medium and solar light(heat) absorption/accumulation performance. The size of the pores(micropores) can be adjusted through the choice of the kind of biomassor carbonization condition. However, in the case of applications of thepresent invention, the major diameter of the aperture of the pore shouldrange 100 μm or less, preferably from 5 to 50 μm. The ratio (ratio ofarea) of pores (micropores) is at least 10%, preferably from 20 to 70%.And, such biomass char can be manufactured by any conventional method.For instance, particles of bagasse char, which is the squeezed waste ofsugarcane, can be manufactured by the following method.

Sugarcanes harvested from a sugarcane field have their roots, leaves,and heads chopped off and then shipped to a sugar milling factory.Thereafter, while hot water or steam is being sprayed over them, thesugarcanes are crushed through several passes of metal rollers tosqueeze an amount of sugar juice therefrom. With this, there is producedan amount strained lees (bagasse) substantially free of sugar. As thisbagasse contains some water, the bagasse is dried at a temperature of100° C. or higher prior to carbonization thereof. Preferably, thisdrying process is performed in a non-oxidizing atmosphere of e.g.nitrogen atmosphere, in order to restrict quality change. After drying,heating carbonization is performed also in a nitrogen atmosphere in e.g.a standard electric furnace. As the heat source for carbonization, aheat source of external heating, a self-combustive heat sourceconfigured to cause combustion of a part of the bagasse, etc. areemployed. In case the carbonization is performed in an experimentallaboratory, with flowing of nitrogen gas in a muffle type electricfurnace, heating is effected from the normal temperature to apredetermined temperature, normally 200° C. or higher, preferably from300 to 1000° C., more preferably from 400 to 900° C., at the rate oftemperature raising of 5 to 50° C. If the temperature increase rate isfaster than 50° C., this tends to invite non-uniform temperaturedistribution. Conversely, if the temperature raising rate is slower than5° C., this is disadvantageous economically. Once the predeterminedtemperature has been reached, the heating is continued at that reachedtemperature for at least e.g. 1 hour, preferably 2 to 5 hours. If theheating time is shorter than 1 hour, this will tend to invite formationof partial mottles due to uneven heating. Whereas, if the heating timeis too long, it is not only economically disadvantageous, but also caninvite quality deterioration. Preferably, after heating, the flow ofnitrogen is continued and cooling to the room temperature is effected bynatural cooling. In this way, black carbon made from raw material ofbagasse (bagasse char) is obtained. This bagasse char is then pulverizedby e.g. a blender, and also classified if necessary, whereby particlesof bagasse char are obtained.

Preferably, the above-described particles have a bulk specific gravityof 0.3 g/ml or less, preferably from 0.05 to 0.2 g/ml approximately.Incidentally, the bulk specific gravity is a value determined byJISK7365-1999 (method of obtaining an apparent density of a materialthat can be poured from a specified funnel: ISO60:1977).

Further, the above-described particles preferably have a particlediameter of 3 mm or less, more preferably, from 0.01 to 1 mm. If theparticle diameter is confined within this range, the dispersion into themedium is favorable. And, particles having such particle diameter can beobtained by classifying with a sieve. That is, particles of 3 mm or lesscan be obtained by collecting those passing through 6-mesh sieve. Also,particles of 0.01 to 1 mm can be obtained by collecting those passingthrough the 16-mesh and then collected on the 170-mesh sieve. Theprecise particle size of each individual particle can be observed with amicroscope. However, errors can occur due to the variation of the shapesthereof. Therefore, for practical use, particles of appropriate sizecollected with using the above-described sieves should be used,preferably.

In the case of the solar light (heat) absorption material of the presentinvention, particles should be dispersed into a medium by normally 0.01to 5 mass %, preferably from 0.1 to 1 mass %, more preferably from 0.3to 0.7 mass % (referred to simply as “%” hereinafter). Thecharacterizing feature of the present invention resides in that anybiomass char particles, even in dispersion of an extremely low content,can achieve sufficient solar heat absorption/accumulation effect andsolar light (heat) absorption/control effect. Dispersing of particlesinto the medium can be performed by any standard method. For instance, arotary blade type stirring machine having various kinds of stirringblades, a vibration type stirring machine having vibration plates, arotary type stirring machine which effects stirring by rotation, aliquid-flow type stirring machine configured to effect stirring bygenerating or colliding liquid flow, a ball mill, an extruder having arotary screw, etc. can be employed. In general, in case the dispersioncontent of the particles is high and the viscosity of the medium ishigh, a rotary blade type stirring machine, or an extruder will beemployed. Whereas, in case the dispersion content of the particles islow and the viscosity of the medium is low, any stirring machine otherthan an extruder can be used. Further, the degree of dispersion can bereadily recognized from the outer appearance of the dispersion.

The solar light (heat) absorption material of the present invention canadditionally contain a substance having a phase transition temperaturein the temperature range from 50 to 120° C., with this substance beingout of direct contact with the medium. For instance, in case the solarlight (heat) absorption material is used as a heatabsorption/accumulation material in a solar water heater or the like, itcan sometimes happen that the time of collecting heat by solar radiationis not necessarily in agreement with the time requiring hot watersupplying or air cooling or warming. In such case, if there is provideda substance having a phase transition temperature in the temperaturerange from 50 to 120° C., preferably from 70 to 120° C., with thissubstance being out of direct contact with the medium, it becomespossible to utilize the amount of heat accumulated in this substance atnight time. As such substance, a so-called heat accumulation materialcan be employed. For instance, as some examples thereof, there can becited paraffin, polyethylene wax, polyethylene, alpha olefin copolymer,ethylene methacrylate copolymer, ethylene vinyl alcohol copolymer,modified polyester, polycaprolactone, polybutyl succinate, or an alloyof two or more kinds of these polymers, or a low molecular weightcompound having a melting in the above-specified temperature range.However, in the respect of moldability, readiness of handling, andsafety, it is preferred to use a substance having a molecular weight inthe polymer or oligomer region, e.g. polyethylene, alpha olefin,ethylene vinyl alcohol copolymer, modified polyester, etc. In order toallow such substance to be present not to be in direct contact with themedium, a method of causing the substance to be contained within asubstance having a higher melting point can be employed. For instance, avariety of methods, such as an encapsulating method, a method of fillingthe substance in a tube, a method of filling the substance in acontainer, etc. can be employed. Further, the kind and amount of theheat accumulation material can be determined appropriately, depending onthe use, performance, etc. For instance, if a large amount of heat is tobe used at night time, the amount will be increased. In case ahigh-temperature heat is needed, there will be employed a heataccumulation material having a high temperature melting point.

The heat absorption/accumulation material of the present inventioncomprises the above-described solar light (heat) absorption materialcomprising particles, which have L*value of 30 or less as determined bythe CIE-Lab color system (light source D65), dispersed into a liquidmedium having a specific heat ranging from 0.4 to 1.4 cal/g/t and amelting point of 5° C. or lower. In this way, as the particles of heatabsorption material are dispersed into the liquid medium of heataccumulation material, in association with rise of temperature of theheat absorption material, the heat will be conducted directly to theheat accumulation material present about the heat absorption material.Therefore, the heat loss in the heat conduction process is small.Further, in the case of the convention, in association with temperaturerise of heat absorption material due to its progressive heat absorption,dissipation of heat due to black body radiation from the heat absorptionmaterial per se would inevitably occur. With the present invention,however, since the heat absorption material is dispersed into the heataccumulation material, the emitted heat from the heat absorptionmaterial too can be absorbed by the heat accumulation material, so thatthere occurs less wasteful heat dissipation to the outside, hence, theabsorbing efficiency is high.

A heat absorption/accumulation structure according to the presentinvention is configured such that the above-described heatabsorption/accumulation material is filled within a container having anopening portion thereof covered with a light transmitting body. FIG. 1is a diametrical section view showing one embodiment of the inventiveheat absorption/accumulation structure. Numeral 1 denotes the heatabsorption/accumulation structure as a whole. Numeral 2 denotes thecontainer. Numeral 3 denotes the light transmitting body. Numeral 4denotes a heat insulating material. Numeral 5 denotes the heatabsorption/accumulation material. The material forming the container 2is metal, glass, resin, etc. and preferably this container is coatedwith a heat insulating material of organic foam material such as styrenefoam, urethane foam or glass fiber, inorganic fiber, etc. Further, asthe light transmitting body 3, glass or the like is employed. And, thismember 3 is attached to the container 2 in airtight and inside thereofis filled with the heat absorption/accumulation material 5. Needless tosay, there may be affixed a selective light transmission film forreflecting heat radiation emitted from the heat accumulated medium. Thethickness of the heat absorbing/accumulating layer (liquid depth) shouldbe controlled so as to render a transmittance for light of 550 nm to be10% or less, preferably 5% or less, more preferably 1% or less. Forinstance, in case bagasse char particles are dispersed in water, even ina dispersion content of as low as about 0.3 mass %, the thickness of 10mm will be sufficient for absorbing substantially 99% or more of solarlight (heat). If the light transmittance exceeds 10%, this will causesubstantially no problem in the absorption of solar light (heat), but,there can sometimes occur such problem as heating of the mounting tableor roof installed. With the heat absorption/accumulation structureaccording to the present invention, the accumulated heat temperaturerises with decrease in the thickness of the heat absorption/accumulationmaterial layer. Therefore, it is possible to adjust the accumulated heattemperature easily and at low cost.

Heat accumulated in the above-described heat absorption/accumulationstructure can be utilized for various kinds of solar heat utilizingapparatuses. For instance, in case water is used as the above-describedmedium, with removal of the particles from the heated heatabsorption/accumulation material with using a conventional separatingmeans such as filtration, the structure can be used directly as a solarwater heater for shower or bathing.

Further, by using the accumulated heat as a heat source of an absorptionrefrigerator or an adsorption refrigerator, the structure can be used asa cooling system. FIG. 2 is a view showing one mode of an absorptionrefrigerator utilizing hot medium such as hot water which hasaccumulated heat by the inventive solar heat absorption/accumulationmaterial as a higher-temperature side heat source. Numeral 11 denotesthe inventive absorption/accumulation structure. Numeral 12 denotes aheat medium pipe. Numeral 13 denotes a regenerator. Numeral 14 denotes acondenser. Numeral 15 denotes a heat exchanger. Numeral 16 denotes anabsorber. Numeral 17 denotes an evaporator. Numeral 18 denotes anabsorbent pump. Numeral 19 denotes a coolant pump. Numeral 20 denotes acooling water pipe. Numeral 21 denotes a medium. Numeral 22 denotes anabsorbent. Numeral 23 denotes a cooling medium. The heat sourcetemperature required on the higher temperature side will vary, dependingalso on the type of absorption refrigerator, but should be at least 65°C., preferably about 70° C. The upper limit thereof is not particularlylimited. For instance, in the case of the multi-stage effect type asshown in FIG. 2, if the heat source temperature is higher, therefrigerator can be made more efficient, such as double-effect ortriple-effect type.

Further, by utilizing the accumulated heat as a heat source fortemperature-difference power generation, this can be constructed as apower generation system utilizing solar heat. The temperature-differencepower generation is a method in which like a marinetemperature-difference power generation, a medium having a low boilingpoint is evaporated/expanded with a higher-temperature heat source andthe resultant mechanical energy is used for rotating a turbine for powergeneration.

A solar light (heat) absorption/control building component according tothe present invention comprises an amount of the above-describe solarlight (heat) absorption material filled within a hollow portion of aplate-like body having the hollow portion. FIG. 3 shows a schematic viewof one embodiment of the solar light (heat) absorption/control buildingcomponent 30 according to the present invention. FIG. 3 (a) is aperspective diagram of the solar light (heat) absorption/controlbuilding component 30 according to the present invention. FIG. 3 (b) isa plan view of the same. FIG. 3 (c) is a front view of the same. FIG. 3(d) is a side view of the same. The solar light (heat)absorption/control building component 30 is configured such that anamount of solar light (heat) absorption material 32 is filled within ahollow portion of a plate-like body 31 and at least one of its upperface 31 a and lower face 31 b has light transmissive characteristics.

The thickness (d) (i.e. the distance between the upper face and thelower face) of the hollow portion filled with the solar light (heat)absorption material 32 can be set as desired in accordance with thepurpose or a required performance. For the purpose of absorption ofsolar light, the thickness is normally not more than 20 mm, preferablyfrom 3 to 10 mm. The greater the thickness, the greater the weight, thusmaking e.g. installment more difficult. Conversely, if the thickness istoo small, the dispersion condition of the particles can sometimes beuneven.

The plate-like body 31 is formed of a glass plate or a thermoplasticresin plate, such as polystyrene, polymethylmethacrylate, polycarbonate,polypropylene, polyethylene, polyethylene terephthalate, polyvinylchloride, polyacetal, polyphenylene oxide, polyvinyl butyral,poly-4-methyl pentene-1, etc., or a thermosetting resin such as melamineresin, epoxy resin, phenol resin, urethane resin, diallyl phthalateresin, unsaturated polyester resin, etc. As for the thickness of theglass plate or resin plate constituting the plate-like body 31, thesmaller size, the lighter weight and the lower cost can be achieved withthinner thickness. However, in consideration of such factors as thestrength, the durability, etc., the thickness is normally between 1 mmor more and 20 mm or less, preferably, between 2 mm or more and 10 mm orless. In particular, in case e.g. the area is 1 m² or less, thethickness of 2 mm or more and 5 mm or less will be sufficient.Incidentally, in order to maintain sufficient thickness of the hollowportion of the plate-like body 31, using a reinforcing member (rib) at aportion thereof will be preferred also. This rib is advantageous alsobecause it controls the flow pathway of the dispersion liquid dischargedtherein. It is necessary that at least one of the upper face 31 a andthe lower face 31 b of the plate-like body 31 have light transmissivecharacteristics. However, if a plate-like body 31 having lighttransmissive characteristics in both faces is provided, it becomespossible to obtain transmission light. The plate-like body 31 can beobtained by bonding glass plates or resin plates together or integralmolding of a resin material by any conventional method. When the solarlight (heat) absorption material 32 is to be filled in the plate-likebody 31, the body will be molded with leaving one face of a glass plateconstituting this plate-like body 31 open or exposed to the outside.Then, an amount of the solar light (heat) absorption material 32 will becharged through the opening and then sealed by bonding the remainingglass plate or the like. Alternatively, an opening may be formed in anintegrally molded plate-like body 31 and then an amount of the solarlight (heat) absorption material 32 may be filled therethrough and thenthe opening will be closed.

With the inventive solar light (heat) absorption/control buildingcomponent 30 having the above-described structure, with the dispersionof particles into the medium, efficient absorption of solar light (heat)is possible. Further, as the emitted heat from the heat-absorbedparticles due to black body radiation is absorbed by the medium,emission of heat to the outside can be minimized, so that the absorptionefficiency of solar light (heat) can be extremely high. For instance, ithas been found that in the case of ethylene glycol liquid containing 0.5mass % of bagasse char particles dispersed therein, if the thickness ofthe space filled with the solar light (heat) absorption material has athickness of 5 mm, light of a metal halide lamp often employed as apseudo solar light can be absorbed as much as 99% or more. This can bedetermined by the method illustrated in FIG. 4.

With the solar light (heat) absorption/control building componentaccording to the present invention, the dispersion content of theparticles into the solar light (heat) absorption material 32 can bechosen as long as the chosen content allows controlling of absorption ortransmittance of the solar light (heat). Further, the content cannot bespecified at a fixed value since it will be varied depending on thethickness of the space between the opposed plate-like bodies 31 also.Normally, however, at least 0.5 mass % is needed in the case ofabsorbing 99% or more of the solar light (heat).

The solar light (heat) absorption/control building component accordingto the present invention allows also adjustment of the light absorbingdegree of the solar light (heat) absorption material based on theoutside condition present in contact therewith. What is referred to hereas “outside condition” can be air temperature, solar radiation amount,but is not limited thereto. The air temperature and solar radiation canbe detected by a thermometer, a solar radiation meter, having arecording stylus capable of automatic input to a personal computer. Forthe adjustment of the absorbance of the solar light (heat) absorptionmaterial, this can be done by varying the dispersion content of theparticles and the thickness. However, changing the dispersion content ismore practical. Specifically, there will be prepared solar light (heat)absorption materials for adjustment with particles contents thereofchanged in a plurality of steps and tanks of water for dilution. Then,by changing the flow rate of the liquid feeding pump attached to eachtank, the particle dispersion content can be changed-as desired. Thatis, when the lightness of the outside is high (bright), the liquidfeeding amount of the solar light (heat) absorption material having ahigh dispersion content is increased so as to reduce the amount oftransmittance light through the solar light (heat) absorption/controlbuilding component. On the other hand, when there is a shortage ofoutside lightness, the amount of water added is increased so as toreduce the particle dispersion content, thereby to increase the amountof transmittance light through the solar light absorption/controlbuilding component. Incidentally, determination of the dispersioncontent of particles can be effected by forming a transparent portionhaving a predetermined path width (e.g. 10 mm) and passing light havinga predetermined wavelength (e.g. 550 nm) and determining its absorbance.In this way, through adjustment of the absorbance of the solar light(heat) absorption material according to the outside condition, it ispossible to maintain constant the amount of solar radiation transmittingthrough the solar light (heat) absorption/control building component.

The solar light (heat) absorption/control building component accordingto the present invention can be provided in the form of a windowpane, aroof tile or roofing material. Specifically, the solar light (heat)absorption material can be held and contained within a double-layeredlight-transmitting windowpane, so that the resultant assembly can beused as a window. This permits adjustment of transparency, adjustment ofsolar radiation amount and adjustment of the indoor temperature. Thishas many features such as being less expensive and requiring lessdriving power than the known photochromic material. Further, in the caseof providing in the form of a roof tile or roofing material, it is alsopossible to cause the inventive solar light (heat) absorption materialto be contained within an intermediate layer of a light-transmittingroof tile or flat roofing material. With this, it becomes possible toadjust the solar radiation amount from the roof and the temperature.Conventionally, in order to permit introduction of solar light from theroof, there was employed a stationary type glass plate. This sufferedfrom the problem of introduction of solar light into the room even onhot summer day, thus causing the room temperature rise. On the otherhand, with the present invention, adjustment of light absorbance ispossible through adjustment of the content of the particles in the solarlight (heat) absorption material, so that it is readily possible toshield solar radiation in the summer and to allow introduction ofadditional solar radiation in the winter.

Further, the inventive solar light (heat) absorption/control buildingcomponent can be installed as a wall, roof or the like of anagricultural/horticultural facility or can be provided in the form of aroofing material or wall material of an agricultural/horticulturalfacility. The solar light (heat) absorption material can control theamount of solar light (heat) permitted into theagricultural/horticultural facility in order to obtain the effect ofabsorbing or controlling/adjusting the solar light (heat), thereby toallow restriction of temperature rise inside the facility or theadjustment of the light amount. In “Okinawa”, the amount of solar lightduring daytime of summer season can be as much as 2500 μmol/m²/sec(micro mol/square meter/second). Whereas the amount of solar lightneeded for summer vegetables is from 200 to 300 μmol/m²/sec, so that theculturing of summer vegetables is almost impossible due to too strongsunbeam. However, if the inventive solar light (heat) absorption/controlbuilding component is used as a ceiling material or wall material of anagricultural/horticultural facility or installed in an exterior wall,roof, etc., thereby to enable adjustment of the solar light, suchculture will be made sufficiently possible. Further, by adjusting thelight absorbance through adjustment of the amount of particles dispersedinto the solar light (heat) absorption material, the adjustment oftransmittance of the solar light is made possible as describedhereinbefore. Then, using this function, there is achieved a significantadvantage as follows. Namely, when the solar light is small at themorning or evening time, the dispersion content will be reduced so as toincrease the transmission amount of the solar light whereas when thesolar light is large at the daytime, the dispersion content will beincreased so as to reduce the solar light transmission. In these ways,the amount of solar light reaching the indoor can be properly adjusted(see FIG. 12). This is a major characterizing feature of the inventivebuilding component.

The solar light (heat) absorption/control building component accordingto the present invention can be installed in a window, wall, roof orrooftop of a standard house or building. With this, heating of the houseor building due to the solar light (heat) can be significantly reduced.For instance, by installing this material in a window, it becomespossible to adjust the amount of sunbeam transmittance. Further, if itis installed in a wall, roof or rooftop, the material will work as anextremely high performance heat insulating material.

That is, as described above, as the particles are dispersed into adispersion liquid, control of light absorbance is made possible asdesired through adjustment of its content, the material can achieve thesignificant function of controlling the transmittance of the solar light(heat). And, if this adjusting function is linked with the solar lightduring daytime, it becomes possible to adjust the solar light and thesolar light introduction time as described. This is a novel method ofadjusting the solar light, solar light introduction time or indoorenvironment adjustment for an agricultural/horticultural facility or astandard house or building.

The solar light (heat) absorption material in the inventive solar light(heat) absorption/control building component can be confined within thehollow portion of the plate-like body. Alternatively, this material canbe circulated to/from an external instrument such as a tank. For thiscirculation, a pump is used normally. Instead, a natural circulationarrangement will also be possible which utilizes change in the specificgravity of a medium whose temperature has risen due to absorption ofsolar light (heat). And, by means of circulation, the solar heatabsorbed and accumulated in the solar light (heat) absorption materialcan be utilized separately.

Further, the solar heat absorbed in the solar light (heat) absorptionmaterial contained in the inventive solar light (heat)absorption/control building component can be converted into hot water orhot air, which is then used directly as hot water or heating air in aprivate residential house, office building or factory. Alternatively,the heat can be converted into cold water or cooling air also. Forinstance, if the material is used as a high-temperature heat source ofan absorption refrigerator or an adsorption refrigerator, coolingindoors is made possible. More specifically, hot water converted fromthe solar heat can be used as it is as a high-temperature heat source ofan absorption refrigerator or can be used as a main heat source of thedischarge heat input type gas adsorption water heater, whereby cool aircan be produced. In this way, through combination of the solar light(heat) absorption/control building component utilizing char particlesfrom biomass and the discharge heat input type gas adsorption watercooling/heating machine, it becomes possible to realize acooling/heating system having high energy saving performance througheffective utilization of renewable energy.

EXAMPLES

Next, the present invention will be described in greater details withreference to some examples. It should be understood however that thepresent invention is not limited thereto. Incidentally, the notation of% unit will be used to represent the unit of mass % unless expresslyindicated otherwise.

Example 1 Preparation of Bagasse Char (1)

In this example, there was employed a squeezed waste-(bagasse) ofsugarcanes produced in Miyako Island in Okinawa in the year 2008.Firstly, the bagasse was dried under nitrogen gas flow at 100° C. for 12hours. The bagasse thus obtained was in the form of milky white fineparticles of 10 mm or less. Then, this bagasse was charged into anelectric furnace and then heated progressively under nitrogen gas flowfrom the room temperature to 500 or 700° C. at the rate of 5° C./min.Once the predetermined temperature reached, a carbonization was carriedout with keeping the temperature at the reached predeterminedtemperature for 5 hours. Thereafter, with continued flow of nitrogen,cooling was carried out to the room temperature by natural cooling.After this, it was found that all the bagasse had turned into black char(bagasse char). Then, this bagasse char was pulverized, for 10 minutes,at the rotation speed of 14000 by a laboratory blender made by stainlesssteel. After this pulverization, particles passing through a stainlesssieve (mesh opening: 150 μm) were collected. It was found that all ofthese particles were uniform and had good fluidity as well. The eachvalue (L values and bulk specific gravity) were obtained as follows.500° C. (27:2, 0.077), 700° C. (29.0, 0.0863). Incidentally, the bulkspecific gravity values were evaluated according to JISK7365-1999, amethod of obtaining an apparent density of a material that can be pouredfrom a specified funnel: ISO60: 1977).

Example 2 Pseudo Solar Light Absorption Experiment (1)

Into a petri dish of 10 cm in diameter, ethylene glycol (EG) liquidcontaining the bagasse char (500° C.) obtained in EXAMPLE 1 at thecontents of 0% and 0.5% were charged to a depth of 1 cm and thensubjected to irradiation by a commercially available halogen lamp(available from Toshiba Corporation) as a pseudo solar light whoseoutput was adjusted to provide a light amount of 2800 μmol/m²/sec(corresponding to the solar radiation amount in summer time in the cityof Naha) and the amount of light past through the petri dish wasdetermined. The light amount was determined by a commercially availablephoton quantum meter. From an EG liquid (Comparison Example) with nobagasse char content, photon quantum of 2660 μmol/m²/sec was determined,thus it was found that irradiated light was hardly absorbed thereby. Onthe other hand, the photon past the EG liquid with 0.5% dispersion ofbagasse char was 0.9 μmol/m²/sec, indicating that 99.97% of light wasabsorbed thereby. The result of this experiment is shown in FIG. 4.

From the above-described experiment, it was found that with dispersionof as little as 0.5% of bagasse char, medium of 1 cm thickness iscapable of completely absorbing solar light (heat). With increase ofdispersion content, complete absorption is possible with even smallerthickness than the above. Further, at this time since the bagasse charabsorbing solar light (heat) is dispersed into the medium, the absorbedheat will be conducted immediately to the medium present around it. Thiscan be called direct heating, in comparison with the method of theconventional solar heat collector which heats medium indirectly. Hence,the efficiency can be very high. Even with a very small thickness, theheat collecting efficiency can be rendered 100% and such reducedthickness can contribute to lighter weight and readiness of installmentover a large area.

Example 3 Absorption Characteristic Experiment (1)

In order to observe in details the light absorption characteristics ofthe bagasse dispersion liquid, there were observed LTV-visibleabsorption spectra of EG (Ethylene Glycol) media whose dispersioncontent of the bagasse char obtained in EXAMPLE 1, carbonized at 500° C.and past the 100 mesh were varied to 0% (comparison example), 0.1%,0.5%, respectively. As the metering cell, there was employed a quartzcell 10 mm in width and 10 mm in thickness. And, the reference in themeasurement was EG liquid with no bagasse char content. The measurementwas done on the transmittance spectrum of light from the 200 nm to thenear infrared region of 1100 nm. The results are shown in FIG. 5.

FIG. 5 shows that with the 0.1% dispersion content, transmittance wasfrom 30 to 35% in entire wavelength region. Whereas, with the content of0.3% or higher, the medium shows only transmittance of less than 1%only, thus demonstrating absorption of almost all light. Incidentally,the discontinuity at 350 nm in the graph is due to a mechanical reason,namely, change of the light source. This result has substantially samemeaning as the result of EXAMPLE 2. Further, the showing of intermediatedegree of transmittance with 0.1% demonstrates that the presentinvention, when used in a window, has the function of adjusting thelight or solar radiation amount.

Example 4 Temperature Rise Experiment

The bagasse char (500° C.) obtained in EXAMPLE 1 was dispersed into EGliquid at the content of 0.5% and EG liquid with no addition of bagassechar was employed as the control. Like EXAMPLE 2, this dispersion wassubject to irradiation by a pseudo solar light having intensity of 1997μmol/m²/sec (corresponding to solar radiation amount in the city of Nahanear summer) and rise of temperature of the liquid inside over time wasrecorded. The result is shown in FIG. 6.

From this result, it is understood that the 0.5% bagasse char dispersedEG liquid provides higher rise in inside liquid temperature than thecontrol. The intercept in the curve is also shown in the figure. Theslopes thereof are 9.5° C./min in the case of the bagasse char 0.5%dispersed EG liquid and 2.7° C./min in the case of the control. That is,it is shown that with the present invention, temperature rise of 50° C.in 5 minutes can be expected. This is an extremely high temperature risenot reported in the convention. In the above, as the dispersion mediumfor bagasse char, EG liquid was employed. It was found that with use ofEG, temperature of 100° C. or higher can be readily obtained which is atemperature not easily obtained with water. Incidentally, the reason whythe temperature rise occurred in EG liquid per se without any bagassechar content is that EG absorbs infrared light of 1200 nm or higher.

Example 5 Preparation of Bagasse Char (2)

Bagasse obtained from a sugar milling factory (Miyako island) wascarbonized at 300 to 800° C. Specifically, the carbonization treatmentof bagasse was performed with use of the following method andconditions. The bagasse from the factory was dried as it was under N₂ at100° C. for 24 hours, thus placed under absolute dry condition. Next,this was put into a muffle furnace and under N₂ gas flow, thetemperature was progressively raised from the room temperature to apredetermined temperature (300 to 800° C.) at a predeterminedtemperature rise rate of 5° C./min. After reaching the predeterminedtemperature, this temperature was held for 3 hours for carbonization.Thereafter, the temperature was lowered back to the room temperature bynatural cooling, whereby bagasse char was obtained. Tables 1 and 2 belowshow the results of properties observed in the resultant bagasse char.While all of these are good chars, as may be apparent from the a,b-values, the char obtained at 300° C. or lower was found slightlydifferent from the others in the respects of color tone, carbonizationratio (total carbon amount). However, its L* value is 30 or lower,hence, being sufficiently usable in the present invention. Further, SEMphotos of the obtained chars are shown in FIG. 7. (a) shows an SEM photoof the char obtained at the carbonization temperature of 300° C. (b) isan SEM photo of the char obtained at the carbonization temperature of400° C. (c) is an SEM photo of the char obtained at the carbonizationtemperature of 500° C. (d) is an SEM photo of the char obtained at thecarbonization temperature of 600° C. (e) is an SEM photo of the charobtained at the carbonization temperature of 700° C. (f) is an SEM photoof the char obtained at the carbonization temperature of 800° C. It maybe seen that all of these chars have good microporous condition. Fromthe photos, it was seen that the pore sizes were approximately 10 μm.Also, the bulk specific gravities (densities) were all very low. In theexamples shown in Table 2, they were not more than 96.3 (mg/cc). Hence,it was found that the chars exhibit favorable dispersion characteristicsdue to these microporous properties and low specific gravities. Further,it was found that the great number of micro pores had significant effecton the absorption of solar light (light). Then, the obtained bagassechars were fine-pulverized in a blender (HB250S, from Hamilton) and thensieved through 100 mesh made of stainless steel, and the bagasse charshaving particle diameters (150 μm or less) past the mesh were collected.

FIG. 8 shows transmittances in the UV-visible (UV-VIS) ranges of thebagasse dispersions containing the fine particles of the above bagassechar in EG (ethylene glycol) at the content of 0.1%. Incidentally, asthe control, EG per se was used. The numerals shown on the right side inthe figure indicate carbonization temperatures. From them, it was foundthat change in the carbonization condition changes the transmittance butthe wavelength does not cause significant change in the transmittance.As for the carbonization temperature, it was found that the bagassedispersions prepared with the carbonization temperatures of 400, 500,600 and 800° C. provide low transmittances, thus effectively absorbingthe light in this range.

Incidentally, for determination of color difference, a color-differencemeter (CR-300) manufactured by Minolta was employed. Bagasse char wasput into a non-light transmissive plastic container and thedetermination was made with placing the color-difference meter ingapless contact with the bagasse char. The light employed was D65(having a light temperature of 6500° C. and corresponding to daylightcolor). For the color difference representation, L*-value, a-value andb-value of CIE color system were employed. The specific bulk gravity wasevaluated by JISK7365-1999 (method of obtaining an apparent density of amaterial that can be poured from a specified funnel: ISO 60: 1977).Further, for the determination of total carbon content (TC), on driedsamples before classification, NO₂ and CO₂ were measured with thecombustion method (NC-90 A, Shimadzu Corporation) and from these values,the total carbon ratio and the total nitrogen ratio were calculated. Inthe determination of the specific surface area, sample degassed for 24hours under vacuum was caused to adsorb N₂ in liquid nitrogen atmosphereand the determination was made with a specific surface area/porosimetrydetermining apparatus (Trister 3000, Shimadzu Corporation). Themicroporous structure of the bagasse char was observed by SEM. For thisSEM observation, gold was coated by the standard method with using anion coater manufactured by Shimadzu Corporation (SS-500) and then theobservation was carried out. UV-VIS determination was made by thestandard method with a spectral photometer manufactured by ShimadzuCorporation (UV-1600PC).

TABLE 1 carbonization temp. 300° C. 400° C. 500° C. 600° C. 700° C. 800°C. appearance coarse coarse coarse coarse coarse coarse (visualparticles particles particles particles particles particles judgment)blackish black black black black black brown total carbon 53.5 70.1 76.8  82.8  85.9  86.0 ratio TC (%) specific  1.9 31.8 214.3 384.2394.6 395.5 surface area (m²/g) SEM photo FIG. 7 FIG. 7 FIG. 7 FIG. 7(d) FIG. 7 FIG. 7 (a) (b) (c) (e) (f)

TABLE 2 Carbonization temp. 300° C. 400° C. 500° C. 600° C. 700° C. 800°C. color L*value 27.4 25.8 27.2 27.9 29.0 25.9 difference a-value 4.181.49 1.74 1.41 1.21 0.77 (CIE system) b-value 4.92 0.82 −1.06 −0.77−0.49 −0.20 specific bulk gravity 81.0 88.7 77.7 87.5 86.3 96.3 (mg/cc)

Example 6 Absorption Properties Experiment (2)

A bagasse dispersion liquid was prepared by using the bagasse char madeat 600° C. in EXAMPLE 5 and EG as a medium. Then, with varying thedispersion content to EG to 0.1%, 0.5%, 1%, the light transmittance inthe UV-VIS range was evaluated like EXAMPLE 5. The UV-VIS determinationswere made by the standard method with using spectral photometermanufactured by Shimadzu Corporation (UV-1600PC). The relationshipbetween the bagasse char dispersion content and the transmittance in theUV-VIS region is illustrated in FIG. 9. With 0.1%, the transmittance ofabout 30% was exhibited in all the wavelength range. But, withdispersion contents 0.5% or higher, substantially no light transmittancewas found. That is, it was found that control material havingappropriate solar light transmission can be obtained by adjustment ofthe dispersion content of bagasse char.

Example 7 Pseudo Solar Light Absorption Experiment (2)

A bagasse dispersion liquid was prepared by using the bagasse charcarbonized at 600° C. of those made in EXAMPLE 5 and EG as a medium.Then, evaluation of light transmittance with the pseudo solar radiationby the same method as in EXAMPLE 2 and an experiment of temperature risein the bagasse dispersion liquid were conducted. The light intensity ofthe pseudo solar light (four 500 W metal halide lamps) was adjusted to2800 μmol/sec/m². This value corresponds to the intensity of solar lightduring daytime in summer of the city of Naha. The bagasse chardispersion liquid (liquid depth 5 mm) was placed between the pseudosolar light source and a sensor (photon counter) and light transmittingtherethrough was determined by the sensor. In the case of absence of thebagasse char (EG only), 95% of light was transmitted. Whereas, in thecase of 0.5% bagasse char dispersion, 99.97% of light was absorbed(0.03% of light was transmitted). With a similar experiment system,dispersion liquids with changing the bagasse char content to 0%, 0.1%,0.3%, 0.5% were placed by the pseudo solar light and rise of temperaturein each bagasse dispersion liquid was determined by a thermocouple. Theresults are shown in FIG. 10. While a certain level of temperature risewas observed even in the absence of bagasse char, with dispersion of thebagasse char, there were observed temperature rises depending on thedispersion content. Assuming a slope of intercept of temperature risecurve at the 0 minute irradiation time represents a temperature riserate, then, in the case of 0%, the rate was 2.7° C./min; in the case of0.1%, the rate was 5.4° C./min; in the case of 0.3%, the rate was 7.5°C./min; in the case of 0.5%, the rate was 9.5° C./min; thus showing theperformance of absorbing the pseudo solar light (heat) was increasedwith increase of the bagasse char dispersed. This tendency isillustrated in FIG. 11. From the extrapolation values of FIG. 11, it wasfound that bagasse char dispersion achieves high temperature rise ratesof 15° C./min with 1% dispersion and 27° C./min with 2% dispersion.

Example 8 Change in Dispersion Content of Particles

The main characterizing feature of the present invention is the abilityof readily and freely changing the ability of the solar light (heat)absorption/control of the solar light (heat) absorption material throughchange in the addition amount of the particles to be dispersed in themedium. The light amount of pseudo solar light was varied to about 500,1000, 1500, 2000, 3000 μmol/sec/m², and there were prepared solar light(heat) absorption materials (bagasse dispersion liquids) with varyingthe dispersion content of bagasse char with unit increment of 0.1% upfrom 0 to 0.5%. And, for the purpose of simulating lightness (Lx) insidean agricultural house with each light amount, the number of photonstransmitting through the solar light (heat) absorption material (liquiddepth: 5 mm) was determined, with taking sufficient care that no lightmay enter from beside the photon counter in the apparatus shown in FIG.4. The results are shown in Table 3.

Further, lightness values and transmittance values with setting thevalue with bagasse char content of 0% to 100 in the data shown in Table3 are shown in Table 4 and FIG. 12. Where there are some irregularities,there was obtained a substantially same light transmittancevalues-bagasse char content curve. From this, it was found that evenwith significant change in the light amount, the pseudo solar light(heat) absorbing performance of the bagasse char hardly changes.Further, from this curve, it can also be understood how the bagasse charcontent should be changed in order to allow transmission of a constantlyfixed amount of solar light (heat) under varying solar light. Forinstance, the intensity of solar light in a day increases after sunriseand reaches maximum in midday and becomes 0 with sunset. A day inagriculture is repetition of this cycle. However, unless the strongsunbeam during midday is controlled, crops such as vegetables will notgrow well. For instance, by utilizing this result, it is readilypossible to maintain the intensity of solar light inside a house (e.g.200 μmol/sec/m²). FIG. 13 shows how the bagasse char dispersion contentof bagasse char dispersion liquid should be changed in order to be ableto control the intensity of transmitted pseudo solar light to 200μmol/sec/m² when the pseudo solar light is varied from 0 to 3000μmol/sec.m². For instance, when the intensity of the pseudo solar lightis 500 μl mol/sec/m², the bagasse char dispersion content should beabout 0.06%. When the intensity of the pseudo solar light is 1500μmol/sec/m², the bagasse char dispersion content should be about 0.15%.When the intensity of the pseudo solar light is 3000 μmol/sec/m², thebagasse char dispersion content should be about 0.21%. In this manner,even in the case of an outdoor agricultural house, the intensity of thelight inside the house can be controlled constant.

TABLE 3 pseudo solar light lightness bagasse char content (w %)μmol/sec/m² 0 0.1 0.2 0.3 0.4 0.5 3066 3066.0 1253.7 251.7 132.3 16.31.3 2538 2538.0 1066.0 203.7 61.0 8.3 0.4 2020 2020.7 836.7 143.7 32.00.5 0.3 1518 1518.0 543.0 63.3 21.3 0.1 0.1 1016 1016.7 503.0 31.0 17.30.1 0.1 505 505.0 178.0 18.0 8.7 0.1 0.1

TABLE 4 pseudo solar light lightness μmol/ bagasse char content (w %)sec/m² 0 0.1 0.2 0.3 0.4 0.5 3066 100 40.9 8.21 4.32 0.53 0.043 2538 10042.0 8.02 2.40 0.33 0.016 2020 100 41.4 7.11 1.58 0.02 0.015 1518 10035.8 4.17 1.41 0.01 0.007 1016 100 49.5 3.05 1.70 0.01 0.010 505 10035.2 3.56 1.72 0.02 0.020

Example 9 Cooling Load Simulation

Simulation experiment on change in cooling load in summer time wasconducted in a standard concrete stand-alone house (building area 64 m²,all two-storeys building) simulating summer time in Okinawa Prefecture,in which a solar light (heat) absorption/control building component(heat collecting plate, liquid depth 5 mm) made by using the solar light(heat) absorption material made of the 0.5% dispersion liquid of thebagasse char (600° C.) prepared in EXAMPLE 5 was installed on a roof oran exterior wall. FIG. 14 are views showing conditions of the solarlight (heat) absorption/control building component on a house in Cases0-3. For making the simulation simple, no window was provided. Theresults are shown in FIG. 15. Comparison example (Case j) is the casewhen such solar light (heat) absorption/control material is notinstalled. At the midday when the sun light is strongest, power of about11.5 kWh is needed. On the other hand, when the inventive solar light(heat) absorption/control building component was installed on a part ofthe roof (20 m²) (Case 1), the power needed for cooling dropped to 9.7kWh. When the inventive material was installed on the entire roofsurface (64 m²) (Case 2), the power needed for cooling dropped to 6 kWh.Further, when the inventive material was installed on the entire roofsurface and the exterior walls (each 48 m²) on the east and west sides(Case 3), the power needed for cooling dropped to about 4.6 kWh. Hence,it may be understood that when the inventive solar light (heat)absorption/control building component is installed on a roof and/orexterior wall of a stand-alone house, the cooling load can be reducedsignificantly.

INDUSTRIAL APPLICABILITY

With the present invention, it is possible to obtain a solar light(heat) absorption/accumulation material with simple structure, low cost,and providing a high performance, which can be used in a solar heatutilizing apparatus such as a water heater or a cooling system or powergenerating system. Further, the solar light (heat) absorption/controlbuilding component according to the present invention is usable in awindowpane or roofing material in a house/building or in anagricultural/horticultural facility.

DESCRIPTION OF REFERENCE MARKS

-   -   1 heat absorption/accumulation structure    -   2 container    -   3 light transmitting body    -   4 heat insulating material    -   5 heat absorption/accumulation material    -   10 absorption refrigerator    -   11 heat absorption/accumulation structure    -   12 heat medium pipe    -   13 regenerator    -   14 condenser heat exchanger    -   16 absorber    -   17 evaporator    -   18 absorbent pump    -   19 cooling medium pump    -   20 cooling water pipe    -   21 medium    -   22 absorbent    -   23 cooling medium    -   30 solar light (heat) absorption/control building component    -   31 plate-like body    -   31 a upper face    -   31 b lower face    -   31 c side face    -   32 solar light (heat) absorption material

1. A solar light (heat) absorption material comprising particles, whichhave L*value of 30 or less as determined by CIE-Lab color system (lightsource D65), dispersed into a liquid medium having a specific heatranging from 0.4 to 1.4 cal/g/° C. and a melting point of 5° C. orlower.
 2. The solar light (heat) absorption material according to claim1, wherein said medium is selected from the group consisting of water,aliphatic mono alcohol, aliphatic di-alcohol, and hydrocarbon.
 3. Thesolar light (heat) absorption material according to claim 2, whereinsaid aliphatic mono alcohol is selected from the group consisting ofethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, and hexanealcohol.
 4. The solar light (heat) absorption material according toclaim 2, wherein said aliphatic di-alcohol is selected from the groupconsisting of ethylene glycol, propylene glycol, polyethylene glycol,and polypropylene glycol.
 5. The solar light (heat) absorption materialaccording to claim 2, wherein said hydrocarbon is selected from thegroup consisting of paraffin, benzene, xylene, and chlorobenzene.
 6. Thesolar light (heat) absorption material according to claim 1, whereinsaid particles comprise carbonized materials of biomass.
 7. The solarlight (heat) absorption material according to claim 6, wherein saidcarbonized materials of biomass has micropores.
 8. The solar light(heat) absorption material according to claim 6, wherein said biomasscomprises bagasse.
 9. The solar light (heat) absorption materialaccording to claim 1, wherein said particles have a particle diameter of3 mm or less.
 10. The solar light (heat) absorption material accordingto claim 1, wherein the material comprises, in said medium, a substancehaving a phase transition temperature in the temperature range from 50to 120° C., with this substance being out of direct contact with themedium.
 11. A heat absorption/accumulation material comprising the solarlight (heat) absorption material according to claim
 1. 12. A heatabsorption/accumulation structure having the heatabsorption/accumulation material of claim 11 filled in a containerhaving an opening thereof covered with a light transmitting body. 13.The heat absorption/accumulation structure according to claim 12,wherein a layer of heat absorption/accumulation material has a thicknessfor achieving light transmittance of 10% or less for light of 550 nm.14. The heat absorption/accumulation structure according to claim 12,wherein the heat absorption/accumulation structure is configured toabsorb/accumulate solar heat.
 15. A solar water heater comprising theheat absorption/accumulation structure according to claim 12, wherein amedium for the heat absorption/accumulation material filled in said heatabsorption/accumulation structure comprises water.
 16. A cooling systemusing heat accumulated in the heat absorption/accumulation structureaccording to claim 12 as a heat source for an absorption refrigerator oran adsorption refrigerator.
 17. A power generating system using heataccumulated in the heat absorption/accumulation structure according toclaim 12 as a heat source for a temperature-difference power generation.18. A solar light (heat) absorption/accumulation building componentcomprising a hollow portion and an amount of the solar light (heat)absorption material according to claim 1 filled in the hollow portion ofa plate-like body having an upper face and a lower face at least one ofwhich has light transmission characteristics.
 19. The solar light (heat)absorption/accumulation building component according to claim 18,wherein the solar light (heat) absorption material is circulated to/froman external instrument.
 20. The solar light (heat)absorption/accumulation building component according to claim 18,further comprising a detecting means for detecting a outside conditionand an adjusting means for adjusting the light absorbance of the solarlight (heat) absorption material according to the outside condition. 21.The solar light (heat) absorption/accumulation building componentaccording to claim 20, wherein said outside condition compriseslightness and/or temperature.
 22. The solar light (heat)absorption/accumulation building component according to claim 18,further comprising a converting means for covering the solar heatabsorbed by the solar light (heat) absorption material into hotwater/air or cool water/air.
 23. The solar light (heat)absorption/accumulation building component according to claim 18,wherein said component comprises a windowpane, a roof tile or a roofingmaterial.
 24. An agricultural/horticultural facility using said solarlight (heat) absorption/control building component according to claim 18in its wall and/or ceiling.
 25. A house/building using said solar light(heat) absorption/control building component according to claim 18 in atleast a part of its wall, window, roof or roof top.